Sound reproducer



July 26 1927. 1,637,322

v M. WEIL SOUND REPRODUCER Filed Aug. 14, 1926 2 Sheets-Sheet 1` 2 magali/ll@ ATTORNEYS.

. July 26,1927. 1,637,322

M. wEn.

SOUND REPRODUCER Filed Aug. 14. 1926 2 Sheets-Sheet 2 Patented `luly 26, 1927.-

U-NITED YSTATES PATENT OFFICE..

MAXIMILIAN VQTEIL,A OF NEW YORK, N. Y.

soUND- REPRODUGER.

Application med Angustia 1926. serial No. 129,144.

My present invention relates to sound re of the type mentioned which will reproduce faithfully and realistically without tubby,

throaty. or blaring effect.

Another object is to provide a reproducer of the type mentioned which can be applied with equal facility to each of the various constructions of amplifying systems and 'affords a substantially sound-proof connection from the compression chamber of the reproducer to the amplifying system.

Another objectisl to provide, a sound reproducer of the type mentioned, in which may be used an extremely ,thin and correspondingly vulnerable metal diaphragm, thereby maintaining the inertia'at a minimum. yet one of sufficient stitfne'ss to initiate a strong sound wave, said diaphragm being shielded to preclude tampering therewith from the exterior of the reproducer case, the shielding instrumentality being of character such as to improve the quality of the performance.

Another object is to provide a sound reproducer or sound box of the character described of attractive construction so flat that it can be laid upon a table without danger of marring the same.-

Another object is to provide for the reproducer a mounting connection upon the tone armor other sound conduit, which will avoid leak of sound and yet afford a secure non-wobbling attachment for the reproducer.

The latter object is accomplished by affording a telescopic engagement of the reproducer sleeve with respect to the tone arm or other sound conduit` of sufficient length to avoid wohbling and affording a rubber or other yielding annulus snugly compressed between the sleeve and the conduitto prevent leak of sound -thereat.

Every sound amplifying system has -a characteristic sound impedance depending mi the size` shape and material of which the amplifier wall is made, and varying with the characteristics of the selection being amplified. Entirely satisfactory operation 1s readily attained according to my tests by the use of a sound reproducer having an Aimpedance characteristic matching that of the amplifying lsyst-em amg( the selection being amplilied. Even speciatconstructions :of reproducer matched in impedance for each of the wide variety of sound amplifyl,ing systems in use are not entirely satisfactory for different types of selections.

I have devised a sound reproducer of readily adjustable impedance so that it can,

be adapted to any. amplifying system or selection. If the adjusting feature involved loss of energy in the course from the diaphragm into the .amplifying system the 'matching of impedance would entail sacrificing of volume.

It is, accordingly, an object of the invention to provide a reproducer readily adaptable with regard to its impedance effect and without sacrifice of volume, to the sound characteristics of any amplifier system through which it is to deliver and to each cf various types of selections to be played thereby.-

The latter object is accomplished by providing the sound reproducer with an impedance chamber at the side of the diaphragm opposite the compression chamber, which latter delivers into Athe amplifying s vstem with which the reproducer is asso* ciated. The impedance chamber is not completely sealed but is opened preferably ad justably to a. degree and in manner such as to impose the desired load or impedance upon the diaphragm.-

The impedance chamber has a closure or wall preventing direct blaring emission of sound into the atmosphere from the otherwise exposed face of the diaphragm without. however, producing a muliied or damped effect or cutting down the volume dueto the reproducer. I have accomplishedl this re sult b v avoiding any direct outwardly opening aperture. in the impedance case, the case being, however, provided with loutwardly stamped or embossed bridging parts having lateral slits ori apertures and' serving to reflect'the sound originating at thediaphragm andjto allow it to escape into the air only by lateral diffusion.

The construction of case or closure, set forth has alsoI the important advantage of serving to protect the enclosed vulnerable anti-blaring protectivecover, an adjustable plate. For ready adaptation of the reproducer to the characteristics of the sound conduit or amplifying system, through which itdelivers and in accordance with the pitch -characteristics of the selection, said cover is disposed for convenient manual adjustment, without the need for removing the reproducer fromthe instrument. For this purpose, the face of the reproducer cover vmay be formed with perforations and the adjustable plate with corresponding perforations and may be manually rotated to increase or decrease the effective opening.

Another feature of the invention 1s to provide the thin sheet metal diaphragm with the major portion of the area thereof deflected out of the plane of its rim, whereby the main area of the diaphragm 'becomes a stiff body, vibrating as a unit about its rim as a hinge, and of such form that vibrations originating near the hinge maybe reflected from another part of the diaphragm directly through the sound exit from the reproducer into the amplifying or other conduit system.

side or base of the reproducer case with respect to the form of the `diaphragm as to afford therebetween an amplifying chamber for4 permitting wave front expansion to -a degree, in the passage from the outer part of the diaphragm toward the amplifying system. l-

Another feature is'to provide the mounting sleeve of the reproducer by which the latter is secured upon the tone armor other conduit system, in inobstrusive position, preferably with its entire length countersunk below the limiting plane lof the reproducer case.

The three features last referred to, while each capable of embodiment in a reproducer construction apart from the other two, are all accomplished by the-simple pedient of providing a diaphragm. with the main area thereof conical in form' and with the apex thereof reversely bent inward into the base of the cone, so as to form the diaphragm W-shaped in axial cross-section. The base of the reproducer case within 'which the rim of the diaphragm is preferably lodged is conformed with a crater-like ridge at its inner face, following the general contour of the lconical diaphragm portion and affording the desired divergence from the rim to the'hub. By the use of the coun-tersunk base construction', the supporting sleeve or hub is countersunk below the end face of the reproducer case.

Inasmuch as the -countersunkl arrangement of 'mounting sleeve does not afford room for the usual set screw for connecting the sleeve at. the bayonet slot of the sound box` l provide a. set. screw of much greater length extendingl from the outer periphery of the reproducer case radiall inward to grip the tone arm or to exten into the bayonet slot thereof.

' In the accompanying drawings'in which is shown one of various possible embodiments of the several features of the invention,

. Fig. 1 is a front elevation of one embodiment of my invention, show n as a phonographic'reproducer or sound box,

' Fig. 2is a sectional view taken on the line 2-2 of Fig. 1,

' Fig. 3 is a rear view ofthe apparatus,

Fig. 4 is a sectional view taken on the line ft-4 of Fig. 1,

Fig. 5 is a plan View of a preferred form of diaphragm,

Fig. 6 is a plan view of the cover member, Fig. 7 is a side elevation of the cover member,

Fig. 8 is a front view of the adjustable lclosure member,

Fig.` 9 is an elevation of an alternative form of protective closure,

Fig. 10 is a side elevation of an application -of the instrument for radio use, Another feature is to so shape the delivery Fig. 11 shows a modified form of cover plate corresponding to that of Fig. 9, and

Fig. 12 shows a further modified form of cover plate.

Referring now to the drawings, I' have shown a reproducer embodied as a phonograph sound box, comprising a base member 10 of a case or box having therein a stylus bar carryingannulus 11 fitting into the rim .'12 thereof and a cover plate 13 cut-away as at 14 to straddle the stylus bar carrier 15 and thereby position lit. Between the lstylus bar annulus and the base is clamped the rim 16 of the diaphragm, said rim for accurate hold being interposed between a pair of washers 17 and 18. For assembly, a plurality of screws 19 are extended through the cover member, the stylus bar annulus, the diaphragm and its washers, the screw Shanks `being-threaded into the base 10.

In a preferred embodiment, the diaphragm is made of an extremely thin metal alloy, preferably in the order of .002 in thickness. Substantially the entire area of said diaphragm within the rim is shaped to extend outward toward one side of the rim in ,a conicalforx'n asat 20, the apex of the cone bein reversely bent inward as at 21. The diap ragm is thus shaped so that each axial cross-section is of the general shape of the letter W or in the shape of ac'rater. By this construction, the entire conical deflected part of the diaphragm is sti'ffened, so that its entire area will vibrate substantially as a unit about the rim 16 as a hinging axis.

' or scratching the same.

The particular form of diaphragm described requires a thickness or depth of sound box, much less than it would if the apex were not inturned. The end of stylus bar 22 is attached by a Washer 23 and by solder to the apex of the diaphragm cone 21, as shown in Fig. 4. l

The'reproducer base is formed of a countersunk construction to afford a circular` crater-like ridge 25 extending generally along the corresponding conformation of the diaphragm, but diverging somewhat with respect thereto, as shownin Fig. 3 from the rim of the diaphragm to the center thereof. By this construction, some amplification will result within the reproducer itself, of vibrations originating near the rim of the diaphragm and traveling radially inward between the diaphragm and the base support to the axial outlet sleeve or hub 26. By the countersunk arrangement of reproducer case employed by me, the hub or sleeve 26 may itself be and preferably is completely countersunk, as shown, with its outer extremity substantially in the limiting plane o f the face of the reproducer case. By this construction, the reproduc-er case is devoid of the protruding sleeve or collar commonly employed on sound boxes, so that my construction is not only neater in appearance, but is more easily disposed where limited space is available and can be laid on an article of furniture without danger ofmarring The arrangement of diaphragm and reproducer case described, also affords the advantage that sound waves originating near the rim of the diaphragm and impinging on4 the inner and conical part 21 thereof, would be reflected directly lthrough the outlet sleeve 26.

Thus, in performance, the entire conical area of the diaphragm vibrates as a stiff unit about the rim as an axis and through asubstantial range by reason of the low inertia of the light diaphragm; the wave front originating nearthe rim of the diaphragm, diverges somewhat in its travel radially along the diaphragm between the latter and the box base for amplification and the vibrations that pass radially inward from near the rim of the diaphragm through the compression chamber, are reflected by the inner conical part 21 thereof and projected `into the amplifying system. This combination of actions affords an extremely efficient operation, preserving various overtones and greatly improving the quality of reproduction. It will also be seen that by the diaphragm and base plate conformation employed, I provide an effective area of diaphragm and of compression chamber considerably larger thanu the diameter of the repro'ducer as a whole, withcorresponding increase of volume.

.Tf the side of the diaphragm opposite that in communication with the amplifying system were left completely open, the sound vibrations would escape therefrom with a blaring effect and interfere with the performance. On the other hand, if said opposite side were completely sealed or closed, the considerable buffer effect of the imprisoned air would materially reduce the volume. According to my invention, the reproducer case cover is provided with openings30 closed by a plate 3l having outwardly curved bridging tongues 32 extending completely over the openings, so that nol direct access can be had through the openings fromvthe face of the cover, the

latter appearing to be completely closed in plan View. However, the sides of the outwardly bent bridges are open so that there is fairly free communication from the impedance chamber to the external air. The openings determined by the bridge pieces thus face in the direction of the casing wall surface. The vibrations due to the diaphragm are thus blocked from direct escape, axially of the sound box or' reproducer, out of the impedance chamber and are reflected back at the bridge pieces 32 and only escape by lateral diffusion through the spaces de-r termined by the edges of said bridging pieces. The sound waves escape in a devious indirect or defiected course from one face through the other of the cover member. By this effect, the reproduction is considerably mellowed and 'enriched and the difficulties incurred by keeping the diaphragm entirely lexposed on the one hand, and completely shut offon the other, are obviated.

Vith ordinary reprod-ucers designed to effectively recreate the ordinary range of pitch, the higher pitched sounds, as for instance, those of the piccolo are inadequately rendered, if they become at all audible to the ordinary listener. The effect of my impedance cover is obviously relatively less upon the longer wave lengths of greater energy and more marked upon the shorter or high pitched waves of little energy. It is more particularly the higher range of pitch` with which the impedance load will resonate so that in performance the value of the lower ranges is maintained, and that of the higher ranges of pitch sufciently enhanced to become truly effective, so that the entire range of pitch is adequately recreated.

The air chamber between the diaphragm` and the cover plate thereof, which constitutes the impedance chamber largely determines the characteristics of the reproducer or sound box, the more open the impedance chamber isl to the air, the lighter the resistance to vibration of the diaphragm. A In a properly playing instrument, lthe impedance should be correlated with respect to that (bfl the con-duit or amplifying system with" which the reproducing system is being employed and adjustment should also be effected with regard to the character of selection being performed. Accordingto the present invenltion, such adjustment is effected manually by the simple expedient of providing` thc aperture 30 in the cover plate, preferably 32 extending directly over the openings in thc fixed plate and has its outer ends preferably extending into snug engagement with the finger grip rim 37. Preferably the pivoting pin is locked by means of a nut 38.

againstI the fixed cover member and has a washer 39 below its head fixing the guard plate 31 against rotation.

For proper reproduction, it is desirablethat no sound leakage occur between the reproducer case and the tone arm or other sound conduit upon which the reproducer is mounted. ForV this purpose, I preferably provide a yielding or elastic, preferably a .Y

rubber collar40 over the mounting hub or sleeve 26, said collar having an inner flange 41, by which it is held in .posi/,tion by means of an encircling split ring 42.' The outerend of the collar has an inwardlyextending flange 43, the rim of which will hug or embrace the tone arm end 44 for a soundtight fit when mounted in position. Yet the length of outlet sleeve 26 fits so securely upon the length of tone arm over. which it is tele scoped that. a firm non-wobbling mechanical fit is provided. In the specific construction descri ed, the reproducer base member is preferably also cast integral with an outstanding wall 45 concentric with sleeve 26 and affording a stop for the fiange 41 of the rubber collar which is protected and housed 1n the deep Aannular cavity determined between the sleeve 26 and they wall 45.

Inasmuch .as the usual bayonet slot 46 of the tone armis not accessible in a construction suchjas described, to the set screw ordinarily used for mountin mo'unting sleeve of a soundg box in position, I haye provided the construction shown, comprlslng a set screw 47 of considerable length inserted through the periphery of the sound box at a correspondingly thickened part 48 thereof, into which the threaded portion 49- of the set screw is threaded. Set screw 47 has p oint 50 extending through a correspondmg aperture'fl in' the rubber collar'46 and through the mqunting sleeve 26 into'the -i bayonet slot 46 of the tone arm. Of course, i l1n constructions in which the tone "arm'is not provided with a bayonet slot, the end of a corresponding screw 47 wouldmerely be the protruding jammed againstthe surface of such tone arm.

My diaphragm being of thin material and vulnerable construction, it should be protected against tampering by-insertion of a pencil or other shar object. The anti-blaring cover 31 described, serves to thus protect the face of the diaphragm at the impedance chamber. To prevent tampering from the mounting side of the dia hragm, a spider construction 52 is preferab y cast inte ral with thc reproducer base at the inner en of Ehe mountin Y sleeve 26 thereof.

In a re erred embodiment, the readily ldjustab c closure plate 31 is provided with i finger 53 movable between stops 54 and 55 along a scale 56 on the fixed cover 13. This scale may consist of an ordinary sequence of numbers, such as shown, 1 to 5. There will be a setting of the valve which will produce the best results in such use. This setting may be ascertained by experience and in the case of phonograph records, it may be marked directly thereon, so that the player will readily set the reproducer for an impedance value corresponding to that noted on the record.

In Fig. 9 is shown a modified embodiment of phonograph sound box which lacks the impedance adjusting feature, and has the i anti-blare sound softening protective cover 60. This cover is similar to cover 32 in Fig. 2, except that instead of having spring fingers, the metal of the cover plate is provided with radiating pairs of slits 61 terminating short of the rim thereof andthe metal between the slits is embossed upward or outward to form bridging straps 62 which function in the manner previously described.

In Fig. 10 is shown in elevation merely, a radio speaker unit. the interior of which is not material 'to this invention. and in cluding the usual electroma etically operating diaphragm (not shown?.n This unit embodies a -closure provided with an antitampering flat cover plate 64 identical with that shown in Fig. 9. Fig. 10 clearly shows in side elevation 'the curved formation of the bridging straps 62 shown in plan in Fig. 9.

In Fig. 11 is shown a cover plate of the same general principlew of that of Fig. 9 with the excel tion that the protective sound refiectingbri ging straps 65 do not radiate, but are arran ed aral'lel to each other and of variable engt s corresponding'to theL lengths of chord of the circular cover 66 along which they extend.

In Fig. 12 is shown another slight modification 'in which the bridgin straps 67 are formed between pairs of slits arranged in an ornamental manner, preferably concentrically of the cover plate. L

I claim y 1. A'sound reproducer comprising a casand having openings in a part of said wall,

said openings having cover portions associated therewith which permit emission 0f sound only by lateral diusion.

2. A sound reproducer, comprising a casing having a diaphragm therein and affording a compression chamber at one side of the diaphragm 'and' an impedance chamber at the other side of the diaphragm emitting f' sound vibrations, said impedance chamber having a wall perforated for emission of sound and provided with deflecting means to direct the sound waves passing through said perforations in a devious path from the inner to the outer face of the wall, said compression chamber having a `mount-ing device for attachment of a sound amplifying system and means rendering said connection sound tight.

S. A sound reproducer comprising a cylindrical casing having a vbase and a cover,la diaphragm having its rim clamped in place between said case elements, said base comprising a compression chamber provided with a mounting sleeve, said cover comprising an impedance chamber and having a face plate perforated for emission of sound and provided with deiiectingl means to direct the sound waves passing through said perforations in a devious path from the inner to the outer face of the plate.

4. A soundl reproducer comprising a cylindrical casing havinga base and a cover, a diaphragm having its rim secured in place between saidcasing elements, said base comprising a compression chamber provided with a rigid mounting sleeve to fit a sound conduit, said cover comprising an impedance chamber, having a wall perforated for emission of sound and provided with deflecting means to direct the sound wavespassing throughsaid perforations in a deviouspath from the inner to the outerface of the wall, said rigid mounting sleeveh'aving a yielding annular part associated `therewith to snugly engage said sound conduit.

5. A sound reproducer comprising a cylindrical casing having va base and a; cover, a diaphragmhaving its vrim clamped in place between said casing elementsysaid base comprising` a 4compression chamber provided with a rigid mounting sleeveto it for Vdirect contact with a sound fconduit vto beencircled thereby, said cover comprisingan impedance chamber and `havinga"face 'plate perforated for emission of sound :and provided with deiiecting meansto direct thesoun'd waves passing throughsaid perforations in-fa devious path from` the inner tothe foute'rfsurface of said plate, ysaid rigidmountingsleeve having a yielding annular part associated therewith to snugly engage said sound conduit.

6. A sound reproducer comprising a casing having a thin vulnerable diaphragm therein, said casing having means at one face of said diaphragm for attachment thereof to a sound conduit and having pairs of slits at the opposite face of said diaphragm determining impedance bridges therebetween for devious communicating passage from the inside of the casing to the external air, the entire area 'of said slitted portion appearin closed whenviewed from a direction norma thereto.

7. A sound reproducer comprising a casing including a base and -a cover, said base having means for attachment thereof to a sound amplifier system, a diaphragm clamped at its rim between said base and said cover to prevent communication of air from one side to the other thereof,.the cover member including a plate, the metal between adjacent slitsiin said plate determining bridging members pressed out of the general plane of the plate rto prevent direct manual access from the exterior tothe enclosed diaphragm. while affording communication to the exy terior.

8. A sound reproducer comprising a flanged base member, a cover member having its rim countersunk therein, a diaphragm of thin metal having its rim clamped' between said base and cover members and affording an air tight closure preventing direct passage of air from one side to the other side of said diaphragm within said Ireproducer, said base having a neck portion adapted for attachment to a sound conduit; said cover having a plate with radiating pairs of slits, the metal between said slits being bent outward beyond thefplane of the plate to determine substantially temper proof openings.

9. A sound reproducer including a diaphragm, a casing therefor, having means for connection at one side of the diaphragm to 'a sound conduit, and adjustable closure means for the side of said casing opposite that of said sound conduitfor varying the impedance of the reproducer without sub-v stantialv variation of Vthe volume of sound emitted from the amplifying system.

l0. A sound .reproducercomprising -a cylindrical case, athin metal ldiaphragm therein 'securedfat kits rim with anl air tight seal, one' side-of'said casing'h'aving means for attachment to 5a sound'conduit, the otherside ofsaidcaseV including a4 plurality-of slots, and av manually adjustableclosure forsaid slots by which the eHective area of Said openings may `be varied.:

11; VA sound-reproducer comprising,- a cy-A lindrical case, a thin metal Idiaphragm therein secured at its rim with Yan air tight seal,

thelc'asing'p'art at one sideof. saiddiaphragm having means for attachment to' asound con- 454, side thereof and the impedance chamber at said base and cover and hermetically sealed thereat to prevent communication of air within said case from one side to the other of said diaphragm, said cover including a circular plate with openings therein and a closure p ate having corresponding openings and manually adjustable to` determine the effect-ive area of communication to the exterior.

13. A sound reproducer comprising a cylindrical case having a base portion for attachment to a sound conduit, a cover portion and a diaphragm clamped at its rim between said base and cover and hermetically sealed thereat to prevent communication of air within said case from one side to the other of said dia hragm, said cover including a circular p ate with openings-therein and a rotatabl mounted closure plate havin correspon 'ng' openings and manually adjustable to determine the effective area -of communication tothe external air, and protective means closing said openings and substantiallyA preventing 'insertion of `an object such as a pin while maintaining the effective open vCommunication to the exterior.

14. A sound reproducer comprising a cylindrical base, a cover therefor, a diaphragm clamped at its rim between said base and said cover and effecting an air tight closure between the transmission chamber at one the other side thereof chamber having means said transmission for connectlon thereof to a sound amplifying system,.`said impedance chamber having a cover withA a plurality of slots therein, an adjustable closure disk pivotally mounted 'on said cover and having corresponding slots, the eectlve open area of said slots being determined by the manual adjustment of said closure plate, and a protective plate secured with respect aving outwardly bent lingers su enposed over the openings and sub-v stantially preventing insertion of a pointed object through said o enings.

15. A sound `repro ucer including a case having a diaphragm fixed therein at its rim, 4means for connecting one side of said case to a sound conduit, the space within .said reproducer at the `opposite side of said diaphragm determining an impedance chamber,

said impedance chamber including a cover portion provided with a plurality of integral curved bridging straps determining lateral openings for communication with the external air and presenting a substantially closed uninterrupted surface in plan view, said bridging straps serving to soften the performance of the instrument.

16. A sound reproducer comprising a base, a cover and a diaphragmclamped at its rim between said base and said cover, a substantial part of the central area of' said diaphragm extending to one side of the plane 'of said rim, said base member having its central part extending inward beyond the plane of said rim and having a mounting sleeve, substantially the entire length of which extends between the extreme lateral' faces of the' reproducer case.

` 17. A sound reproducer comprising a case having a base and a cover, a thin metal diaphra gm clamped at its rim between said base and said cover the main portion of the ventral area of said diaphragm extendin to one side of the plane of said rim an` being thereby stiifened to move in vibration subf stantially as a rigid unit with respect to the hinge rim, said base portion having a-central hub part extending inwardinto the deflected part of the diaphragm and a central mounting sleeve substantlally countersunk within' the end face of the case.

18. A sound reproducer comprising a case v Ihaving a baseand a -cover member, a thin metal diaphragm/clamped at its rim between said members', the main area of said diaphragm within said rim being W-shaped1n axial cross-section, the base member bein conformed with a hub extending inwar within the annular crater space determined by the central part of the diaphragm, and having a central'mountin V length of which extends tween the end faces of the case.

19. A sound reproducer comprising a case sleeve the main l having a diaphragm fixed therein at its rim,

4'said case having a mounting exit sleeve for attachment to a sound delivery conduit, and said diaphragm havin an integral crater conformation W-shape in axial cross section the 'inner part of whichwill project into said sound conduit, some of the vibra- Y tions originating near'theouter part thereof.

20. A sound reproducer comprisin a casing, a dia hragm fixed therein ande amped t0 establis an air tight seal between the air chambers within the :case at opposite faces of the diaphragm and having a. conformation; symmetrical withy respect to its center, the case having a delivery outlet, the end face of the case extending from the rim of the diaphragm to said opening diver ing with respect to the diaphragm to alfor an amplifier chamber within the reproducer.

v.21. A sound reproducer comprising a casing, a diaphragm fixed therein and clamped to establish an air tight seal between the air chambers within the case at opposite faces of the diaphragm, said diaphragm having a conformation symmetrical with respect t'o its center, the case having an outlet sleeve the end face of the case extending from the rim ofthe diaphragm to said sleeve diverging with respect to the diaphragm to afford an amplifier chamber within the reproducer, said diaphragm having a reversely extending stiffening part affording a reflector for projecting into the outlet sleeve, sound waves originating near the rim of the diaphragm and impinging on the stifening part.

having a base member and a cover member, a thin sheet metal diaphragm clamped at its periphery between said case parts, said diaphragm being conical in form with the apex portion thereof reversely bent inwardinto the base portion thereof, the baseport-ion of the case having Va crater shaped part extending inward into the generally annular space determined between the base and the apex part of the diaphragm, and a mounting sleeve integral with said base extending outward from said `crater part, with the main length thereof between the end faces of the case.

23. A sound reproducer comprising a case `having a diaphragm fixed therein, a mounting part for said case to communicate with an amplifying system, said case being also open to the air at the side of the diaphragm opposite that facing said 'mounting part,

. means within lthe mounting part preventing tampering with the diaphragm while affording a free exit for sound waves, and means at the opposite side of the casing for like- `wise preventing tampering with the enclosed diaphragm.

24. A sound reproducer comprising a casing having a base member with an integral axial mounting tube countersunk within the outer face of the base member, a spider structure unitary therewith to prevent tamperinga vulnerable thin metal diaphragm within said case member, a closure member secured to said case member and clamping eral contour of the contiguous face of the base member, said closure member having a shield plate appearing closed in plan view and including outstanding parts overlapping lateral openings for communication of the interior of the reproducer `with the external air.

26. A sound repi'oducer comprising a base or isupport member having a sleeve hub of material sufficiently rigid and of diameter and-length sufficient for mechanically secure mounting telescoping engagement directly upon a sound conduit, and a yielding annulus associated with said sleeve hub -to be compressed by and to snugly engage a part o'f vthe sound conduit. 22. A sound reproducer comprising a case 27. A sound reproducer comprising a base, or'support member having a sleeve hub for telescopic fit over a sound conduit and an elastic collar member about said hub having an inturned part lbeyond said hub overla ping the end thereof and determining a su stantially sound-tight connection with respect to the conduit.

28. A sound reproducer comprising a casing having a vibratory sheet metal diaphragm enclosed therein, said casing including an integral mounting sleeve for attachnient to a sound conduit, aj rubber sleeve thereabout, means securing" said rubber sleeve in position, said sleeve having an inturned rim in contact with the extreme edge of said hub for effecting a sound-tight en'- gagement by circumferential engagement vwith the conduit.

29.- A` sound reproducercomprising a ease having an integial countersunk conduit embracing sleeve, anintegral wall concentric with said sleeve and spaced therefrom, a rubber collar having a base flange filling the annular space between said sleeve and said wall, a.,w1re against said base flange securing saiclcollar in position, the outer edge of said collar being inturned over the inner edge of said sleeve toI afford a sound-tight engagement with the tube over which the reproducer hub is to be telescoped.

30. Asound reproducer for a phonograph comprising a diaphragm enclosing casing, the base of said` casing having a mounting sleeve countersunk thereinto, the diaphragm being of a form to accommodate the inner part of the countersunk port-ion, Iand a securing screw extending substantially from the rim of the sound producer case radially inward through the hub for engagement with the end of the tone arm to which'the -sound .reproducer is aflixed.

31.In a phonograph, a sound boxf cromprising -a base, a cover, a diaphragm'W- shaped in axial cross-section, and clamped at its rim between said base and said cover, said base having a countersunk inwardly extending portion to follow the geneial contour of said diaphragm and including a hub portion, substantially the entire length of f which is between the end faces of the casing, and a lon set screw threaded from the perimeter of t e casing through the hub for extension into the bayonet slot of the tone arm mount.

l 32. In a phonograph, a sound box comprising a base, a cover, a diaphragm W- shaped in axial cross-section and clamped at its rim between said base and said cover, said base having a countersunk inwardly extending portion to follow the eneral contour of said diaphragm and including a mounting sleeve portion, substantially the entire length of which is between the end faces of the casing, a long set screw extending from the perimeter of the casing through the sleeve for protrusion `at its inner end into the bayonet slot of the tone arm mount, and a rubber collar encircling said hub and having an inwardly extending rim for snug engagement with the tone arm to render the construction sound-tight thereat, said set screw extending through a corresponding aperture in the elastic collar.

33. A sound reproducer for' a phonograph comprising a base member, a cover member, a diaphragm having its rim clamped between said members, said diaphragm being conical in form with the apex thereof reversely bent inward into the base of the cone, said cover membery being of countersunk formation to follow the general contour of the conical diaphragm and including a mountin sleeve for engagement with. the end of t 1e tone arm, said mounting sleeve being substantially entirely between the limiting end faces of the sound box case, a set screw extending inward from the perimeter of said casing through the thickness thereof and through the sleeve into effective locking engagement with the tone arm, means for preventing leak of sound between the tone arm and the sound box, said means compris! ing an elastic collar encircling said hub, a wire ring securing said collar in position, said collar having an inturned flange at its outer end overlapping the extremity of the sleeve for engagement with the tone arm, said collar having a perforation through which the set screw protrudes, and a proteetive spider integral with theV sound box base for engagement against the extremity of the tone arm, said cover having a. protective shield to prevent tam ring with the enclosed diaphragm, and sai shield having out-standing bri ging parts the edges of which define lateral openings for communication with the external air.

34. A sound reproducer comprising a casing having a vibrator diaphra m held therein at its rim, said iaphragm having a substantial art of the area. thereof extending out of tie plane of the rim thereof, the casing havin a conformation at one face thereof to fol ow the general contour of the diaphragm area., whereby the effective area. of the diaphragm and of the chamber de tei-mined between said casing face and the diaphragm is materially larger than that of the casing.

35. A sound reproducer comprising a base or support member having a sleeve hub of material suiliciently rigid and of sufficient length for mechanically securev mountin lit with respect to a sound conduit, and a yielding annulus associated with said sleeve hub to be compressed by and to snugly enga e a part of the soundl conduit, beyond an of length shorter than that of said sleeve' hub.

Signed at New York city in the county of New York and State of New York this 13 day of August, AID. 1926.

' MAXIMILIANYWEIL. i 

